Usually, you can click on the app in the AppStore view and then edit the "package version" in the URL bar before installing. You can determine the package version from https://git.cloudron.io/cloudron/minecraft-forge-app/-/blob/master/CHANGELOG . However, the specific version you are asking for was never packaged since the app was still getting to a stable release.
M
MrJengo
@MrJengo